Patent GB-873605-A (GB)
Title: Improvements in or relating to steroids and the manufacture thereof
IPC: C07J75/00
Filed: 1958-05-21
Abstract: The invention comprises 11 a -alkylated-5a  (and 5b )-pregnanes of the general formula <FORM:0873605/IV (b)/1> wherein R1 represents a keto group or an a -hydroxy group in the case of a 5b -pregnane and a b -hydroxy group in the case of a 5a -pregnane, R2 represents a keto or hydroxy group and the 11-lower alkyl group contains 1 to 8 carbon atoms, and the corresponding 3a - or 3b -hydroxy-20-ketal, 3,20-diketal and 3-ketal-20-one compounds in which the ketal radicals are of the formula <FORM:0873605/IV (b)/2> wherein n is 1 or 2 and R represents hydrogen or an alkyl radical containing 1 to 6 carbon atoms, and a process for the preparation of compounds of the above general formula in which R1 is an a - or b -hydroxy group and R2 is a hydroxy group or R1 and R2 are keto groups by alkylating a 5a  (or 5b )-pregnane-3,11,20-trione 3,20-diketal wherein the ketal radicals have the above general formula with the required alkylating agent to introduce the 11a -alkyl radical, subjecting the resulting 11b -hydroxy-11a -alkyl-5a  (or 5b ) - pregnane - 3,20-dione 3,20-diketal to hydrolysis, e.g. with an acid hydrolysing agent, to form 11b -hydroxy-11a -alkyl-5a  (or 5b )-pregnane-3,20-dione, and then, if required reducing this compound in the presence of an inert solvent to form 3a  (or 3b ), 11b ,20-trihydroxy-11a -alkyl-5b  (or 5a )-pregnane, a process for the preparation of compounds of the above general formula wherein R1 is an a - or b -hydroxy group or a keto group and R2 is a hydroxy group, by alkylating a 5a  (or 5b )-pregnane-3,11,20-trione 3,20-diketal wherein the ketal radicals have the above general formula, with the required alkyl lithium to form an 11b -hydroxy-11a -alkyl-5a  (or 5b )-pregnane-3,20-dione 3,20-diketal, partially hydrolysing this compound in a solvent medium using a dilute concentration of a strong acid to form 11b -hydroxy-11a -alkyl-5a  (or 5b )-pregnane-3,20-dione-3-ketal, reducing this compound to reduce the 20-keto radical to a 20-hydroxy radical, hydrolysing the 3-ketal radical to form 11b ,20-dihydroxy-11a -alkyl-5a  (or 5b )-pregnane-3-one, and then, when required subjecting this compound to further reduction to form a 3a (or 3b ), 11b , 20-trihydroxy-11a -alkyl-5b  (or 5a )-pregnane, a process for the preparation of compounds of the above general formula wherein R1 represents an a - or b -hydroxy radical and R2 is a hydroxy or keto radical by alkylating a 3a  (or 3b )-hydroxy-5b  (or 5a )-pregnane-11,20-dione-20-ketal wherein the ketal radical has the above general formula, with the required alkyl lithium compound to form a 3a  (or 3b ), 11b -dihydroxy-11a -alkyl-5b  (or 5a )-pregnane-20-one 20-ketal, hydrolysing this compound to form a 3a (or 3b ), 11b -dihydroxy-11a -alkyl-5b  (or 5a )-pregnane-20-one and then, when required, reducing this compound to form 3a  (or 3b )-11b ,20-trihydroxy-11a -alkyl-5b  (or 5a )-pregnane, and ketalisation processes for the preparation of the 3a  (or 3b ), 11b -dihydroxy-11a -alkyl-5b  (or 5a )-pregnane-20-one 20-ketal and 11b -hydroxy-11a -alkyl-5a  (or 5b ) - pregnane-3,20-dione 3,20-diketal and 3-ketal where the ketal radicals have the above general formula.  The invention also includes 3-, 11-and 20-monesters, 3,11-, 3,20-, and 11,20-diesters and 3,11,20-triesters of the corresponding hydroxy substituted of the above general formula, and may be prepared by the usual esterification or partial esterification methods or by partial hydrolysis of completely esterified compounds.  A large number of acids from which the ester groups may be derived are specified. Detailed examples are given.  5a -Pregnane-3,11,20-trione 3,20 - bis ketal where the ketal radicals are of the general formula <FORM:0873605/IV (b)/3> wherein n is 1 or 2 and R represents hydrogen or an alkyl radical containing up to 6 carbon atoms, are prepared by reacting 5a -pregnane-3,11,20-trione and the required glycols in the presence of p-toluene sulphonic acid.  Specifications 737,957, 756,562, 794,487 and 829,476 are referred to.